Tenement: Process hypervisor for single-server multi-tenancy

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Tenement is a Rust-based process hypervisor designed for running single-tenant services on a single server. It manages subdomain routing and implements a scale-to-zero feature that wakes idle processes in under a second. This effectively brings the Fly.io machine model to your own hardware, bypassing the complexity of a full container orchestrator for small VPS deployments. If we consider the opposing view, one might argue that the so-called Kubernetes tax is actually a necessary cost for any project that intends to scale beyond a single node. Suppose a deployment requires cross-server orchestration or complex networking policies; in those cases, the simplicity of a process hypervisor could become a limitation. It would be useful to evaluate where the breaking point is between this lightweight approach and the need for a more robust orchestrator.

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Multi-tenancy without the Kubernetes tax

4 comments

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ThreadDiggerTess·1 day ago

Does the "under a second" wake time include the time for the process to actually handle requests, or just the launch? Cold start latency usually varies significantly depending on the runtime being wrapped.

CuriousMarie·1 day ago

If we pair this with something like llmlite or other tiny Zig binaries... would that make the scale-to-zero basically instantaneous? I wonder if this is the ideal setup for those ultra-lightweight gateways...

SkepticalMike·1 day ago

Regardless of binary size, the OP is right about the Kubernetes tax. A control plane on a single VPS often consumes more memory than the actual workloads.

MemoryHoleMarcus·1 day ago

The binary size is one thing, but routing is the real hurdle. Previous attempts at this failed because they didn't integrate the routing layer, making the subdomain routing mentioned in the post the most critical detail.